unique.matrix issue [Was: Anomaly with unique and match]
match() is a red herring here -- it is really a very specific thing that has to do with the fact that you're running unique() on a matrix. Also it's much easier to reproduce:
x=c(1,1+0.2e-15) x
[1] 1 1
sprintf("%a",x)
[1] "0x1p+0" "0x1.0000000000001p+0"
unique(x)
[1] 1 1
sprintf("%a",unique(x))
[1] "0x1p+0" "0x1.0000000000001p+0"
unique(matrix(x,2))
[,1] [1,] 1 and this comes from the fact that unique.matrix uses string representation since it has to take into account all values of a row/column so it pastes all values into one string, but for the two numbers that is the same:
as.character(x)
[1] "1" "1" Cheers, Simon
On Mar 9, 2011, at 9:48 AM, Terry Therneau wrote:
I stumbled onto this working on an update to coxph. The last 6 lines below are the question, the rest create a test data set. tmt585% R R version 2.12.2 (2011-02-25) Copyright (C) 2011 The R Foundation for Statistical Computing ISBN 3-900051-07-0 Platform: x86_64-unknown-linux-gnu (64-bit) # Lines of code from survival/tests/singtest.R
library(survival)
Loading required package: splines
test1 <- data.frame(time= c(4, 3,1,1,2,2,3),
+ status=c(1,NA,1,0,1,1,0), + x= c(0, 2,1,1,1,0,0))
temp <- rep(0:3, rep(7,4)) stest <- data.frame(start = 10*temp,
+ stop = 10*temp + test1$time, + status = rep(test1$status,4), + x = c(test1$x+ 1:7, rep(test1$x,3)), + epoch = rep(1:4, rep(7,4)))
fit1 <- coxph(Surv(start, stop, status) ~ x * factor(epoch), stest)
## New lines
temp1 <- fit1$linear.predictor temp2 <- as.matrix(temp1) match(temp1, unique(temp1))
[1] 1 2 3 4 4 5 6 7 7 7 6 6 6 8 8 8 6 6 6 9 9 9 6 6
match(temp2, unique(temp2))
[1] 1 2 3 4 4 5 6 7 7 7 6 6 6 NA NA NA 6 6 6 8 8 8 6 6 ----------------------- I've solved it for my code by not calling match on a 1 column vector. In general, however, should I be using some other paradym for this "map to unique" operation? For example match(as.character(x), unique(as.character(x)) ? Terry T
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